* @param multiset the multiset for which an unmodifiable view is to be generated
   * @return an unmodifiable view of the multiset
   */
  public static <E extends @Nullable Object> Multiset<E> unmodifiableMultiset(
      Multiset<? extends E> multiset) {
    if (multiset instanceof UnmodifiableMultiset || multiset instanceof ImmutableMultiset) {
      @SuppressWarnings("unchecked") // Since it's unmodifiable, the covariant cast is safe

import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * An implementation of {@code Iterable} which throws an exception on all invocations of the {@link
 * #iterator()} method after the first, and whose iterator is always unmodifiable.
 *
 * <p>The {@code Iterable} specification does not make it absolutely clear what should happen on a
 * second invocation, so implementors have made various choices, including:
 *
 * <ul>

     *     cast to doubles (with any associated lost of precision), and which will not be mutated by
     *     this call (it is copied instead)
     * @return an unmodifiable, ordered map of results: the keys will be the specified quantile
     *     indexes, and the values the corresponding quantile values. When iterating, entries in the

      }
    }
    return true;
  }

  /**
   * Returns a {@code Collector} that returns the {@code k} smallest (relative to the specified
   * {@code Comparator}) input elements, in ascending order, as an unmodifiable {@code List}. Ties
   * are broken arbitrarily.
   *
   * <p>For example:
   *
   * <pre>{@code
   * Stream.of("foo", "quux", "banana", "elephant")
   *     .collect(least(2, comparingInt(String::length)))

    new IteratorTester<String>(
        5, UNMODIFIABLE, Collections.singleton("a"), IteratorTester.KnownOrder.KNOWN_ORDER) {
      @Override
      protected Iterator<String> newTargetIterator() {
        return of("a").iterator();
      }
    }.test();
  }

  @GwtIncompatible // slow (~30s)
  public void testIterator_general() {
    new IteratorTester<String>(

    new IteratorTester<String>(
        5, UNMODIFIABLE, Collections.singleton("a"), IteratorTester.KnownOrder.KNOWN_ORDER) {
      @Override
      protected Iterator<String> newTargetIterator() {
        return of("a").iterator();
      }
    }.test();
  }

  @GwtIncompatible // slow (~30s)
  public void testIterator_general() {
    new IteratorTester<String>(

  private Iterables() {}

  /** Returns an unmodifiable view of {@code iterable}. */
  public static <T extends @Nullable Object> Iterable<T> unmodifiableIterable(
      final Iterable<? extends T> iterable) {
    checkNotNull(iterable);
    if (iterable instanceof UnmodifiableIterable || iterable instanceof ImmutableCollection) {
      @SuppressWarnings("unchecked") // Since it's unmodifiable, the covariant cast is safe

import static com.google.common.collect.Sets.powerSet;
import static com.google.common.collect.Sets.unmodifiableNavigableSet;
import static com.google.common.collect.testing.IteratorFeature.UNMODIFIABLE;
import static com.google.common.truth.Truth.assertThat;
import static com.google.common.truth.Truth.assertWithMessage;
import static java.io.ObjectStreamConstants.TC_REFERENCE;

   * could throw during the invocation of that method. This is necessary because, e.g., a call to
   * {@code iterator().remove()} of an unmodifiable list could throw either {@link
   * IllegalStateException} or {@link UnsupportedOperationException}. Note that iterator
   * implementations should always throw one of the exceptions in a {@code PermittedExceptions}

 *       elements were added (insertion order)
 * </ul>
 *
 * <p>{@code Network}s built by this class also guarantee that each collection-returning accessor
 * returns a <b>(live) unmodifiable view</b>; see <a
 * href="https://github.com/google/guava/wiki/GraphsExplained#accessor-behavior">the external
 * documentation</a> for details.
 *
 * <p>Examples of use:
 *
 * <pre>{@code